Railroad brake shoes



Jan. 20, 1959 R. L. WILSON RAILROAD BRAKE SHOES 2 Sheets-Sheet 1 FiledAug. 10, 1956 27 FIG. 2

INVENTO R. ROSSER L. WILSON ATTORNEYS Jan. 20, 1959 R. L. WILSONRAILROAD BRAKE SHOES Filed Aug 10, 1956 FIG. 6

FIG. 7

ROSSER L. WILS AT TO R N EYS United States Patent RAILROAD BRAKE SHOESRosser L. Wilson, Mahwall, N. J., assignor to American Brake Shoe Com anNew York N. Y. a tion of Delaware p y, corpora This invention relates toa new and improved brake shoe for use in a railway braking system and isparticularly concerned with a new and improved metal backing structurefor a composition type brake shoe.

The brake shoe which has long been standard in the railroad industrycomprises a cast iron body having a substantial thickness and having abraking surface which 18 curved to correspond in general to thecurvature of a railroad car or locomotive wheel. The back, of the castiron brake shoe may include a supporting plate or strip formed fromrolled steel around which the brake shoe body is cast; this supportingmember reinforces the cast lIOIl body and, to a certain extent, servesto hold it together in the event that the brake shoe body is fractured.

during service. Another type of brake shoe which has been suggested foruse on railway cars and locomotives comprises a composition bodysupported on a steel backing plate which is in some respects similar tothe support member of the cast iron type of shoe. In the compositionbrake shoe, the support lugs and other elements for mounting the brakeshoe upon a brake head are formed as a part of or are mounted upon thesupporting back, whereas in the cast iron shoe construction the mountinglugs, toe guides and the like are frequently cast as a part of the brakeshoe body.

There are several distinctive differences between cast iron andcomposition type brake shoes. For example, the composition type shoeprovides substantially higher retarding force per unit braking area,since it achieves a substantially higher coeflicient of friction thanmay be ob tained with a cast iron shoe. In general, it may be statedthat cast iron shoes are low-friction high-pressure devices, whereascomposition shoes are high-friction low-pressure devices. Accordingly,the composition shoe may be employed at substantially lower operatingpressures than the cast iron shoe. The composition type shoe, however,as known in the prior art, has exhibited several disadvantages whichhave precluded general adoption for railroad service. One particularlyimportant difficulty mitigating against general use of composition typeshoes in railway systems has been the tendency of the composition bodyto break under severe operating conditions and to separate from themetal back structure under even mild braking conditions. To a certainextent, this disadvantage may be attributed to the difference in thermalcoefficients of expansion of the composition body and the metal backstructure; in addition, the brake' shoe body may be stressed beyond thebreaking point or may be separated from its metal back due to forcestending to flex the brake shoe which are frequently encountered inrailroad service. Moreover, the relatively severe vibrational forcesencountered in railway service and the substantial shock to the brakeshoe occurring upon initial application of the brakes may tend to detachthe composition body from the metal back and/ or to fracture the shoebody.

It is an object of the invention, therefore, to overcome 'orsubstantially minimize the above noted disadvantages of previously knowncomposition type railroad brake 2,869,689 Patented Jan. 20, 1959 iceshoes by resort to a specially constructed back for th composition shoe.

A further object of the invention is a new and improved back structurefor a railroad brake shoe of the composition type which. providesinherently better resistance to fiexural forces and shock thanpreviously known constructions without requiring separate and additionalreinforcing members.

A corollary object of the invention is a new and improved brake shoe ofthe composition type including a back structure which provides maximumadherence to and interlocking with the composition body of the shoe.

It is an important object of the invention to provide a new and improvedback structure for a composition type railroad brake shoe which issubstantially stronger than conventional composition brake shoe backsbut which is inherently economical to manufacture.

Thus, the invention is directed to a back structure for use in arailroad brake shoe of the type comprising a molded composition bodysupported upon a metal back which is adapted to be mounted upon a brakehead, the brake shoe body having a predetermined length, width, andthickness and having a predetermined curvature along its length. Theterm composition as used throughout this specification and, in theappended claims is defined as meaning a comminuted friction material ina heat resistant organic binder such as a rubber, a resin, or arubber-resin mixture. A back structure constructed in accordance withthe invention comprises a metal support member, preferably of rolledsteel, having a length, width, and curvature approximately correspondingto the length, width, and curvature of the composition body. A pluralityof intersecting diagonal ribs are formed integrally with the metalsupport member, preferably in the rolling operation; these ribs projectfrom the concave surface of the. support member and serve to interlock.the composition body with the support member. The height of theinterlocking ribs is made substantially smaller than the thickness ofthe composition body of the brake shoe. In

addition, a plurality of individual metal projections are affixed to andextend from the support member to provide additional interlockingbetween the support member and the composition body, the height of theseprojections also being substantially smaller than the thickness of thecomposition body. Preferably, these individual metal projections areformed by punching out individual portions of the support member. Theinvention is applicable to railway brake shoes intended for use onlocomotive driver templated applying these principles. Other embodimentsof the invention embodying the same or equivalnet principles may be usedand structural changes may be made as desired by those skilled in theart without departing from the present invention and the purview ofthe'ap pended claims.

In the drawings:

Fig. 1 is an elevational view, partly in cross section, of a railway carbrake shoe constructed .in accordance with one embodiment of theinvention;

Fig. 2 is a plan view of the railway car brake shoe illustrated in Fig.1;

Fig. 3 is a bottom view of the metal back structure of the brake shoe ofFig. 1;

Fig. 4 is a cross-sectional view taken along line 44 in Fig. 1;

Fig. 5 is a detail sectional view taken along line '5'5" in Fig. 2;

Fig. 6 .is an elevation view, partly in cross section, ofa driver shoeconstructed in accordance with the invention;v

Fig. 7 is a plan view of the driver shoe of Fig. .6;

Fig. 8 is a bottom view showing the metal back structure of the brakeshoe of Fig. 6; and

Fig. 9 is a cross sectional view taken .along line 99 in Fig. 6.

The brake shoe 20 illustrated in Fig. 1 comprises a metal support member21 utilized to support a molded composition braking body 22. Supportmember 21 is preferably fabricated from either hot-rolled or cold-rolledsteel, hot-rolled steel usually being preferred. Composition body 22 maybe molded from any composition material suitable for railway brakingservice, depending to some extent uponthe type ofcar or locomotive towhich the brake shoe is to be applied. A preferred type of compositionmaterial, which exhibits superior characteristics with respect to heatand shock resistance and which afiords a favorable ratio of wet to drycoefi'icients of friction, is described and claimed in the copendingapplication of R. E. Spokes et al., Serial No. 491,510, filed March 1,1955, and assigned to the same assignee as the present invention. Thispreferred type of composition comprises a comminuted friction material,selected from the .sillimanite and related aluminum silicates,distributed in a heat-stable rubber binder; additional friction materialin theform of cast iron particles may also be included.

Composition body 22 may be provided with two or more vents 23 in thebraking surface thereof to assist in'uniform curing-of the compositionthroughout its thickness and to aid in difiusion of heat during brakingservice. .As indicated in the drawing, composition body 22 has apredetermined length and width and a substantial thickness and has apredetermined curvature along its length .to conform with the curvatureof the wheel to which it is applied during braking service. Supportmember 21, in general, corresponds approximately in length, width, andcurvature to the composition body, although exact dimensionalcorrespondence is not essential and minor variations may be effectedwithout substantially affecting the invention.

A pair of longitudinal flanges or projections 24 and 25 extend from theedges of support member 21 into clamping engagement with compositionbody 22, as best illustrated in Fig. 4. The height of flanges 24 and 25should be made relatively small as compared with the thickness ofcomposition body 22in order to avoid the possibility that the metalflanges will be brought into contact with the wheel to which the brakeshoe is applied after the .brakeshoe has seen substantialservice.Otherwise, .thefianges may tend to score the wheel or toleave metaldeposits thereon, since the temperatures reached during braking serviceare frequently high enough to partially melt the metal back structureand weld it to the wheel if the two come in contact with each other.Flanges 24 and 25 serve to bind the composition body andmetal backstructure of the brake shoe to each other and also add to the rigidityof the backstructure.

Support member 21 and composition body 22 .arealso interlocked with eachother by means of a plurality of individual metal projections aflixed toand extending from support member 21 into the composition body. Theseindividual metal anchors are most conveniently and economically formedby punching out individuaLportions 26of support member 21 to form thedesired anchor elements. As in the case of the longitudinal :flanges,the efiectiveheight of projectionsZfi should be ;made sub st;antiallysmaller than the thickness of compositionbody Moreover, individualportions of support element 21 adjacent flanges 24 and 25 may be punchedout and portions of composition body 22 may be molded into theresultingapertures 27 to provide further anchor points he Figs. 1 and 2.

ber 21, as illustrated in Fig. 3. preferably formed in support member 21by rolling in tween support member 21 and composition body 22. Thisconstruction, with the multiple interlocking between composition body 22and support member 21, as thus far described, is essentially similar tothat described and claimed in the copending application of E. EllsworthCaton et al., Serial No. 603,405, filed concurrently herewith andassigned to the same assignee as the present invention.

Although the metal back structure described in the aforementioned Catonet al. application is extremely advantageous as compared with previouslyknown composition brake shoe structures and is very well suited for manytypes of railroad service, it may frequently be desirable to provide asubstantially stronger back structure for the more severe operatingconditions encountered in some railway systems, One construction whicheffectively achieves this objective is described and claimed in mycopending application, Serial No. 603,403, filed concurrently herewithand assigned to the same assignee as the present invention. In theconstruction described in that application, a separate metal reinforcingmember is employed to strengthen the brake shoeagainst fiexure and toafford sOme degree of additional interlocking between the support memberand the composition body. In the present invention, these sameobjectives re achieved by an entirely different structure comprising aplurality of intersecting diagonal ribs 28 projecting from the under orconcave surface 29 of support mem Diagonal ribs 28 are the early stagesof fabrication of the metal support member and thus constitute anintegral part of the support member. As in the case of anchorprojections26 and flanges 24 and 25 the effective height of ribs 28 should be madesubstantially smaller than the thickness of comp sition body 22 in orderto prevent metalto-metal contact between support member '21 and thewheel to which the brake shoe is applied. Interlocking ribs 28 provide amultiplicity of additional interlocking elements which add substantiallyto the effective adherence between composition body 22 and supportmember 21. In addition, the diagonal ribs make the support member muchstiffer than would otherwise be the case and thus provide a markedincrease in the ability of the brake shoe to resist deformation fromilexural and other forces encountered during service. Moreover, itshould be noted that, in the ribbed structure of the invention, asubstantially greater number of anchorage points such as those providedby projection elements 26 and apertures 27 may be provided withoutunduly weakeningsupport member 21, thereby further improving theadherence of composition body 22 to the support member.

7 In accordance with conventional practice, brake shoe 20 may beprovided with a center attaching lug 30 preferably formed as a separatesteel member and clinched into apertures in support member 21, asindicated in The centerlug30 is provided with the usual keyway and isadapted to be mounted on abrake head in conventional manner. Thebrakeshoe may also be provided with a plurality of end stops 31, 32, 33,and

34 in accordance with conventional practice; preferably, the end stopsare fQ i ed as integral parts of support member 21 and comprisingpunched or otherwise bent sections of the support member extending aboveits convex surface 37. Brake shoe 2!) may also be provided with a pairof toe guides35 and 36 at the opposite ends thereof; in the illustratedconstruction, the toe guides comprise integral lugs formed as apartofsupporhrnem- .ber 21 in the same manner as the .brakeshoeandstops.

It should 'beunderstoodthatthe rnountingarr ngement to be mounted; inthis connection, attention is directed to application Serial No.606,868, filed August 29, 1956, and to application Serial No. 606,869,filed August 29, 1956; both of these applications, which are assigned tothe same assignee as the present invention, describe stantialimprovement in the performance characteristics 7 of railway car brakeshoes in that it affords a much more rigid back structure for the brakeshoe and at the same time provides markedly better adherence between themetal backing structure and the composition brake body. The qualities ofrigidity and superior adherence between the parts of the brake shoeafforded by the inventive construction, however, are even more importantin locomotives, since the shocks, vibrational forces, and otherdisturbing factors present in all railway service are usually mostprevalent at the driver wheels. Thus, the advantages afforded by theinvention are even more important in a driver brake shoe of the typeillustrated in Figs. 6-9.

The driver brake shoe 40 shown in Figs. 6-9 is in many respects quitesimilar to brake shoe of Figs. 1-5 and comprises a composition body 41supported upon a metal back structure 42. As indicated in Fig. 6, brakeshoe body 41 has a predetermined length and a predetermined longitudinalcurvature; support member 42 is of approximately the same length and hasa curvature generally coring section 41A of substantially rectangularcross-sectional configuration and having a predetermined thickness; a

second or flange-engaging portion 41B extends from one side oftread-engaging section 41Aand is arched or curved to fit the flange of adriver wheel (not shown). Flange-engaging section 41B of the compositionbody is not of uniform configuration throughout its length; rather as,indicated in Figs. 6 and 9, the central portion of the flange-engagingsection is relieved so that it does not contact the wheel flange whenthe brake shoe is first placed in service. This discontinuous orsectional flange structure is conventionally employed to preventchattering of the driver brake shoe during the initial or wear-in periodof service.

Support member 42 also comprises two sections, a tread section 42A whichgenerally conforms to the configuration of tread-engaging section 41A ofthe composition body, and a flange section 423 which extends from oneside of tread section 42A and is curved to conform, in general, to theconfiguration of flange-engaging section 413 of the brake shoe body.Sections 42A and 42B of support member 42 are preferably formed from asingle sheet of rolled steel to provide the strongest possible backstructure. As in the embodiment of Figs. l5, composition body 41 may befabricated from any composition material suitable for railway brakeservice, preferably that described in the aforementioned Spokes et al.application.

Both tread section 42A and flange section 42B of support member 42 arepreferably provided with a plurality of individual metal projections 46which extend a relatively short distance into composition body 41 tointerlock support member 42 to the composition 'body; as in thepreviously described embodiment, the height of these anchor projectionsshould be made substantially smaller than the thickness of thecomposition body into which they extend in order to preventmetal-to-metal contact between the brake shoe and the wheel. Asindicated in Figs. 7 and 9, anchor projections 46 are preferably formedby punching out individual areas in support member 42., The brake shoemay also be provided with the usual center attaching lug 47 comprising aseparate steel member clinched into apertures provided therefor insupport member 42, as shown in Fig. 7, and provided with the usualkeyway. A pair of end stops 48 and 49 may be formed at the opposite endsof support member 42 by suitably bending the support member upwardlyfrom is convex surface in order to afford a means for preventinglongitudinal motion of the brake shoe with respect to a brake head uponwhich it is mounted.

As in the previously described embodiment, and in accordance with theinvention, a plurality of intersecting diagonal ribs 50 are formedintegrally with support member 42 on the under or concave surfaceSI-thereof; di agonal ribs 50 project fro-m the concave surface of thebrake shoe into interlocking engagement with composition body 41. Theheight of ribs 50 should be made substantially smaller than thethickness of the composition body at any given point to avoid scoring ofthe wheel surface and to prevent welding of the brake shoe to the wheel.In the preferred construction illustrated, the diagonal ribs are notconfined to flange section 42A of the brake shoe support member, butextend into flange section 428 in order to interlock both portions ofthe support member with the corresponding sections of the compositionbody and to provide the desired rigidity and stiffness in the flangesection as well as the tread section of the brake shoe. Ribs 50 thusserve to strengthen the entire brake shoe backing structure and at thesame time to afford substantially improved interlocking between thecomplete composition body and the metal support element. As in theembodiment of Figs. 1-5, ribs 50 are preferably formed by rolling ofsteel support member 42 before the metal is punched and otherwise shapedto form the support member. Because ,of the added strength and rigidityprovided by ribbed support member 42, a relatively large number ofindividual metal anchors 46 may be formed in the support member withoutweakening it, thus permitting the achievement of substantially improvedadherence between the support member and the composition body withoutsacrificing essential strength characteristics.

Hence, while I have illustrated and described the preferred embodimentsof my invention, it is to be understood that these are capable ofvariation and modification, and I therefore do not wish to be limited tothe precise details set forth, but desire to avail myself of suchchanges and alterations as fall Within the purview of the followingclaims.

I claim:

1. In a railroad brake shoe of the type comprising a composition bodysupported upon a metal back which is adapted to be mounted upon a brakehead, said brake shoe body having a predetermined length, Width, andthickness and having a predetermined curvature along said length, a backstructure comprising a metal support member having a length, width andcurvature approximately corresponding to the length, width and curvatureof said composition body; and a plurality of intersecting diagonal ribsformed integrally with said metal support member and projccting from theconcave surface thereof for interlocking said composition body and saidmetal support member, the height of said ribs being substantiallysmaller than the thickness of said body; and a plurality of individualmetal projections affixed to and extending from the concave surface ofsaid support member to interlock said support member with saidcomposition body, the height of said projections being substantiallysmaller than the thickness of said body.

2. in a railroad brake shoe of the type comprising a composition bodysupported upon a metal back which is adapted to be mounted upon a brakehead, said brake shoe body having a predetermined length, width, andthickness and having a predetermined curvature along said length, a backstructure comprising a rolled steel support member having a length,width, and curvature corresponding approximately to the length, width,and.

7 sarvatur nt a Com e i n dy; a lu l t f i er secting diagonal rihsrolled into said steel support member as an integral part thereof,projecting from the concave surface thereof for interlocking saidcomposition body and said steel support member, the height of said ribsbeing substantially smaller than the thickness of said body; and aplurality of individual metal projections aflixed to and extending fromthe concave surface of said support member for interlocking said supportmember with said composition body, the height of said projections beingsubstantially smaller than the thickness of said bo y- 3. In a railroadbrake shoe of the type comprising a composition body supported upon ametal back which is adapted to be mounted upon a brake head, said brakes oe sd h v n a prede erm e l W th, and thickness and having apredetermined curvature along said length, a back structure comprising arolled steel support member having a length, width, and curvatureapproximately corresponding to the length, Width, and curvature of saidcomposition body; a plurality of intersecting diagonal ribs rolled intosaid steel support as an integral part thereof, projecting from theconcave surface thereof for interlocking said composition body and saidsupport member, the height of said ribs being substantially smaller thanthe thickness of said body; and a plurality of individual metalprojections, comprising punched out portions of said steel supportmember, for interlocking said support member with said composition body,the height of said projections being substantially smaller than thethickness of said body.

4. In a railroad brake shoe of the type comprising a composition bodysupported upon a metal back which is adapted to be mounted upon a brakehead, said brake shoe body havinga predetermined length, Width, and

thickness and having a predetermined curvature along said length, a backstructure comprising a rolled steel support member having a length,width, and curvature corresponding approximately to the length, width,and curvature of said composition body; a plurality of intersectingdiagonal ribs rolled into said steel support member as an integral partthereof, projecting from the concave surface thereof for interlockingsaid composition body and said steel support member, the height of saidribs being substantially smaller than the thickness of said body; aplurality of individual metal projections affixed to and e t din mt s cn a r c of d uPPQ t me ber for interlocking said support member Withsaid cornposition body, the height of said projections beingsubstantially smaller than the thickness of said body; and a pair oflongitudinal flanges formed as an integral part of said steel supportmember and extending into clamping relationship with the sides of saidcomposition body,'said flanges having a height substantially smallerthan the thickness of said body.

5. In a brake shoe for a railroad driver wheel of the type comprising acomposition body supported upon a metal back which is adapted to bemounted upon a brake head, said brake shoe body comprising atread-engaging section having a predetermined length, width, andthickness and a predetermined curvature along said length and furthercomprising a flange-engaging section extending from one side oi saidtread-engaging section and having a lateral curvature generallycorresponding to the curvature of a driver wheel flange, a backstructure comprising: a steel support member comprising a tread sectionhaving a'length, width, and curvature approximately corresponding to thelength, width, and curvature of said tread-engaging section extendinglaterally from said tread section and having a lateral curvatureapproximately corresponding to that of said flange-engaging section ofsaid composition body; a plurality of intersecting diagonal ribs rolledinto said steel support member as an integral part thereof, projectingfrom the concave surfaces of said tread and flange sections of saidsupport member tor interlocking said composition body and said supportmember, the height of said ribs being substantially smaller than thethickness of said body at any given point; and a plurality of individualmetal projections afiixed to and extending from both said body andflange sections of said support member for interlocking said supportmember to the said composition b dY, the height of said projectionsbeing substantially smaller than the thickness.

References .Cited in the file of this patent UNITED STATES PATENTSWinters July 3 L934

